Asphalt-asbestos mastic and method for producing same



Patented Feb. 4, 1936 PATENT orricc ASPHALT-ASBESTOS MASTIC AND METHODFOR- PRODUCING SAME Ulric B. Bray, Palos Verdes Estates, Lawton B.Beckwith, San Pedro, and Frederick S. Scott, Los Angeles, Calif.,assignors to Union Oil Company of California, Los Angeles, Calif., acorporation of California No Drawing. Application June 23, 1934, SerialNo. 732,118

12 Claims. (01. 106-31) This invention relates to an asphalt mastic andto a method for producing the same. The invention relates particularlyto an asphalt mastic containing a fibrous material such as asbestoswhich is adapted to be used as a flooring, to coat refrigeration pipesand refrigerator walls,to provide a finish coat over cork or magnesiainsulation and in general, to be employed as a protective coating andalso to be used for filling cracks,

10 for caulking and the like.

It is an object of our invention to produce an asphalt mastic which maybe readily troweled when applied to the surface to be coated and whichis relatively cheap to produce.

15 Another object of the invention is to produce an asphalt mastic inwhich the asphalt is evenly distributed over the aggregate or fibercontained in the mastic and to produce a mastic which is entirelyhomogeneous.

20 The present day commercial asphalt mastics are generally prepared bymixing Pickering (clay) type emulsified asphalt with, for example, suchmaterials as asbestos fiber, and water. In this process, melted asphaltis mixed with a slurry of 25 a colloidal mineral such as bentonite inwater to produce an asphalt in water emulsion and the asbestos is thenadded totheemulsion. This mixture is then troweled over the material tobe protected. When the mixture dries out a hard 30 coating resultscomprising the asbestos fiber, as-

phalt and the emulsifying agent, i. e. clay. It has been found that whenthis type of emulsion is examined under microscope, the mastic con sistsof a suspension of asbestos fiber and water 35 intermixed with smallparticles of asphalt which, however, are not fixed upon the fiber. Wehave discovered that a superior productmay be produced and one which'iseasy to apply, that is, will not adhere to the trowel when applied tothe 40 surface to be coated and one in which the asphalt adheres to theasbestos fibers so that when set up the resultant membrane contains amore even dispersion of asphalt since every fiber is coated withasphalt. This phenomenon increases the homo- 45 geneity of the mastic.

In general, we may produce an asphalt mastic forming the subject of ourinvention by mixing a fibrous material such as asbestos fiber, withwater 50 until the fiber is uniformly moist. This mixture is thencommingled with emulsified asphalt and is thoroughly mechanically mixedin such an apparatus, as, for example, a pug mill, until the emulsionhas completely broken down and all the 55 asphalt is deposited upon thefibers. The mastic is then ready to be applied to the surface to becoated.

An important feature of the invention resides in the addition of smallquantities of de-emulsifying agents such as sulphuric acid and moreparticularly, hydrated lime or calcium hydroxide, to the mastic in suchcases where the emulsion, after a reasonable amount of working, such asby trowelling indicates that the complete deposition of the asphalt uponthe fibers has not occurred. In order to prevent the material frombecoming sour, we may add a small amount of 40% formalin solution to themastic.

After the deposition of the asphalt upon the fibers, a certain amount ofwater is added and, finally, a certain quantity of finely divideddiatomaceous earth. The finely divided diatomaceous earth acts as alubricant so that improved trowelling characteristics are obtained.

It is another important feature of the invention to add a small amountof a stabilizer, preferably sodium caseinate, that is, casein containinga small amount of sodium hydroxide, to the asbestos fiber and watermixture prior to the introduction of emulsified asphalt into themixture. If the asbestos fiber is dispersed in water and then mixed withthe asphalt emulsion without addition of sodium caseinate to themoistened fibers, the resultant mixture may become lumpy due to toorapid breaking of the emulsion and is difficult to trowel even whendiatomaceous earth is added. However, by adding the sodium caseinate(containing sodium hydroxide) to the asbestos-water mixture prior toadmixture with emulsified asphalt, a fine grained mixture of goodtexture which is relatively soupy is obtained. The prior addition of thesodium .caseinate to the moistened asbestos fibers prevents the asphaltfrom breaking out in large lumps or globules upon the surface of theasbestos fibers. When the asphalt emulsion is added to a solution ofasbestos containing sodium caseinate, the emulsion is intimatelydispersed with the asbestos forming a homogeneous mixture of water,asphalt in minute particles, asbestos and sodium caseinate. The lattermixture may then be broken slowly to the desired consistency fortrowelling either before or after addition of diatomaceous earth orwithout the addition, of diatomaceous earth. adding a de-emulsifyingagent slowly to the mixture such as sulphuric acid, slaked or unslakedlime, calcium chloride, or Portland cement. This .disperses the minuteglobules or particles of asphalt onto the asbestos with an outside water55 This may be accomplished by film which makes the asphalt-asbestosmastic readily trowelable. v

The following is a more detailed description for producing anasphalt-asbestos mastic forming the subject of our invention. However,it will be observed that the following description is merelyillustrative of one mode of carrying out our invention and is not to beconsidered as limiting. l

- 100 parts by weight of asbestos fiber are' mixed with 150 parts ofwater until the fiber is uniformly moist; then about 5 parts of a watersolution containing 10% casein and 0.5% caustic soda are added slowly tothe moistened asbestos fiber and thoroughly mixed therewith. To thismixture are added 180 parts of asphalt emulsion containing approximately55% by. weight of asphalt which has been stabilized with sodiumcaseinate. The addition is made slowly and with suitable stirring' untilthe mixture becomes a thick paste of unbroken. emulsion and asbestos.

In order to break the asphalt onto the asbestos fibers, approximately 50parts of a slurry containing 33% hydrated lime are added. Wehave foundthat slaked limeis the most satisfactory material for breaking theasphalt particles onto the'asbestos fibers because it breaks down theemulsion most evenly and also because it tends to hold water in the massand make it more readily trowelable. However, we do not limit ourselvesto the use of slaked lime, since other material as unslaked lime,calcium chloride or Portland cement may be employed for the purpose ofbreaking the emulsion. Finally, one part of commercial 40% formalinsolution is added to the mixture, which acts as a preservative for thecasein so that the material will not become sour. After the emulsion hasbroken and the asphalt has deposited upon the asbestos fibers, we maythen add about 40 to 50 parts of water, as desired, to bring the mixtureto the desired trowelling consistency.

After the addition of the water to the foregoing asphalt-asbestosmastic, approximately 20 parts of finely divided diatomaceous earthmixed with the asphalt-asbestos mastic and this mixture is then appliedto the surface to be protected, such as, for example, when covering corkor magnesia insulation. The mixture is preferably trowelled and isapplied to the surface to be coated in thicknesses of, say to A; in.thick. Upon hardening, a smooth surface coating is produced in which theasphalt is distributed evenly over the fibers, thus increasing thehomogeneity of the mastic.

The asphalt emulsion heretofore mentioned which was added to theasbestos, water and sodium caseinate mixture may be produced by meltingat a temperature of, say 320 F., 60 to 62 parts by weightof asphaltproduced from Poso solution is thoroughly mixed with the melted asphalt.At this point, the alkali content of the mixture is about 0.12 to 0.14%sodium hydroxide. The agitation by means of the circulating pump iscontinued until the asphalt is finely dispersed in the caustic sodasolution. This emulsion is then cooled to approximately to F. bycirculating through cooling coils and then a solution of sodiumcaseinate which has been prepared by mixing with 20% by weight of caseinwith the proper amount of cold water, digesting for about one to twohours and then adding 1% by weight of sodium hydroxide with additionalagitation is injected into the cooled emulsion as the latter is beingcirculated in and out of the emulsifying tank through the centrifugalpump. The amount of casein solution is gauged so that approximately only1% of casein is incorporated into the asphalt emulsion. Then a smallamount of commercial 40% formaldehyde solution or formalin is mixed withthe asphalt emulsion. To this mixture is next added further quantitiesof water so that the asphalt content is reduced to approximately 55 to56%. This emulsion may then be stored and used as needed' While we havedisclosed the addition of stabilizer to the asphalt emulsion and also tothe asbestos fiber, it will be observed that sodium caseinate need notbe added to the asphalt emulsion and that the required amount of caseinmay be added only to the moistened asbestos.

Instead of employing casein as a stabilizing agent for the asphaltemulsion or for adding to the moistened asbestos fiber, we may use otherprotein type materials such as glue and blood albumen or carbohydratematerials as starch, gum acacia, agar agar, algin, gum tragacanth,pectin, Irish moss, etc. As preservatives for the stabilizer in order toprevent the asphalt emulsion or the asphalt-asbestos mastic to formfermentation or other decomposition, we may employ other preservativesthan the formaldehyde or formalin as above mentioned, such as cresol,phenol, sodium benzoate and the like.

Instead of producing the emulsified asphalt as above, that is, byemulsifying the sodium hy droxide alone, we may employ other emulsifyingagents such as rosin or rosin oil soaps, sodium stearate, sodiumpalmitate and salts such as sodium phenate, carbonate, sodium silicateand the like. The asphalt emulsion may be stabilized as desired.

Instead of producing an asphalt mastic containing asbestos fibers asdisclosed above, we may produce asphalt masticsv containing otherfibrous materials as paper pulp or rag pulp, manila, jute, coconut,cotton, wool, hair or other fibers. Also, instead of applying theinvention to the production of an asphalt mastic containinga fibrousmaterial, we may apply the invention to produce mastics containingground minerals as limestone, jasper, clay or diatomaceous earth eitherfree from fibrous materials, or in admixture with such fibrousmaterials.

The important consideration isthat the stabilizer is added to the fibersand/or ground minerals and water prior to'admixture with the asphaltemulsion. If desired, mineral aggregate, such as sand, crushed stone andgravel. may be commingled with the mastic containing the fibers prior toapplying the same to surfaces. In such cases, the aggregate may be addedto the mastic subsequent to the breaking of the asphalt onto the fibers.

The foregoing exemplary description is not to be considered as limitinsince many variations elled on surfaces comprising afibrous material,

asphalt, water, a stabilizing agent, a de-emulsifying agent and a finelydivided material which will adapt said mixture to be readily appliedonto a surface by means of a trowel.

2. A paste which is adapted to be readily trowelled on surfacescomprising a fibrous material, asphalt, water, a stabilizing agent, ade-emulsifying agent and diatomaceous earth.

3. An asphalt-asbestos mastic comprising asbestos, asphalt, sodiumcaseinate, water and hydrated lime.

4. An asphalt-asbestos mastic comprising 100 parts by weight ofasbestos, 150 parts of water, 5.5 parts of a solution containing 10%casein and 0.5% caustic soda and 180 parts of asphalt emulsion. l

5. An asphalt-asbestos mastic as in claim 4 and containing approximatelyparts of a slurry containing 33% hydrated lime.

6. An asphalt-asbestos mastic which is adapted to be readily trowelledon surfaces comprising asbestos, asphalt, water, sodium caseinate,hydrated lime and diatomaceous earth.

7. An asphalt-asbestos mastic adapted to be applied to surfaces bytrowelling comprising 100 parts by weight of asbestos, 150 parts ofwater, 5.5 parts of a solution containing a stabilizing agent, 180 partsof asphalt emulsion containing approximately of asphalt, 50 parts of awater slurry containing 33% of hydrated lime and 20 parts ofdiatomaceous earth.

8. An asphalt-asbestos mastic adapted to be applied to surfaces bytrowelling comprising parts by weight of asbestos, parts of water. 5.5parts of a solution containing 10% casein and 1.5% caustic soda, partsof asphalt emulsion containing approximately 55% of asphalt, 50 parts ofa water slurry containing 33% of hydrated lime, one part of 40% formalinand 20 parts of diatomaceous earth.

9. A method for producing asphalt mastics adapted to be readilytrowelled on the surfaces to be coated with said asphalt mastic whichcomprises commingling a fibrous material with a quantity of water and astabilizing agent, commingling said mixture with an asphalt emulsion toform a thick paste of unbroken asphalt emulsion and fibrous material,then breaking said asphalt emulsion by adding a de-emulsifying agent topermit asphalt to cling onto the fibers of said fibrous material andsubsequently commingling said mixture with a finely divided granularmaterial so as to adapt said mixture to be readily applied onto thesurface by means of a trowel.

10. A method for producing asphalt mastics adapted to be readilytrowelled on the surfaces to be coated with said asphalt mastic whichcomprises commingling a fibrous material with a quantity of water and astabilizing agent, commingling said mixture with an asphalt emulsion toform a thick paste of unbroken asphalt emulsion and fibrous material,then mixing hydrated lime with said mixture to break said asphaltemulsion and to permit asphalt to cling onto the fibers of said fibrousmaterial and subsequently commingling said mixture with a finely dividedgranular material so as to adapt said mixture to be readily applied ontothe surface by means of a trowel.

11. A method for producing asphalt mastics adapted to be readilytrowelled on the surfaces.

to be coated with said asphalt mastic which comprises commingling afibrous material with a quantity of water and a stabilizing agent,commingling said mixture With an asphalt emulsion to form a thick pasteof unbroken asphalt emulsion and fibrous material, then mixing hydratedlime with said mixture to break said asphalt emulsion and to permitasphalt to cling onto the fibers of said fibrous material andsubsequently commingling said mixture with diatomaceous earth which isadapted to cause said mixture to be readily applied onto the surface bymeans of a trowel.

12. A method for producing an asphaltasbestos mastic adapted to beapplied to surfaces by trowelling comprising mixing 100 parts by weightof asbestos, 150 parts of water and 5.5 parts of a solution containing10% casein and 1.5% caustic soda, mixing said mixture with 180 partsasphalt emulsion containing approximately 55% of asphalt, subsequentlymixing said mixture with 50 parts of a water slurry containing 33% ofhydrated lime and subsequently adding 20 parts of diatomaceous earth.

ULRIC B. BRAY. LAW'TON B. BECKWITH. FREDERICK S. SCOTT.

